An ultrasound diagnostic apparatus sends an ultrasonic wave to the inside of a diagnosing object by an ultrasound probe, receives a reflected echo signal which corresponds to a structure of a biological tissue from the inside of the diagnosing object, and forms a cross-section image, e.g., an ultrasonic cross-section image (B-mode image), or the like, to be displayed for a diagnosis.
In order to collect three-dimensional ultrasonic data, in the typical technique, three-dimensional data obtained by scanning a probe automatically or manually in a short axis direction is subject to coordinate conversion, thereafter ultrasonic image data is reconfigured in a visual line direction, and a three-dimensional image is created, thereby a surface of an object is observed. The recent typical technique is a technique called real-time 3D or 4D, in which signal processing described above is performed in real time, and a moving three-dimensional image is displayed.
Also, in order to observe not a surface but an arbitrary cross-section region of a three-dimensional space, or in order to obtain a detailed image, a typical technique is displaying an arbitrary cross-section region from three-dimensional data.
However, as in the case of a normal two-dimensional cross-section image, the aforementioned techniques have a problem that a diffraction pattern called speckle, which is unique to ultrasound, causes a break in display of regions, which is expected to be continued, or a problem that a three-dimensional structure of an object is not obvious.
Examples of a method for solving the aforementioned problems include a method disclosed in Patent Literature 1. It is disclosed that a technique is selected for rendering volume which is one of surface texture, maximum density, minimum density, average projection, rendering an inclined light, and maximum transparency, in order to display an emphasized C plane image by emphasizing one of the anatomical features.